Art. 1079.01 Detector Loop The inductive loop detector shall have a minimum of two modes of operation, presence or pulse. The inductive loop detector shall be capable of self tuning. The inductive loop detector shall, in a failure condition, register a continuous call to the signal controller. Extend Call – Delay Call. The inductive loop detector shall change from delay mode to extend mode and vice versa at the end of the time set for each mode. The inductive loop detector shall have a means of visually indicating the timings of delay and extension settings are in effect.
b.Special Feature. System Output. In addition to supplying normal timing output, the detector shall be capable of providing a simultaneous system output for traffic volume, occupancy, and speed measuring. The system output shall be constant and not affected by delay or extension timings. This output shall allow either presence or pulse operation which may be selectable from a front panel switch. The presence and pulse outputs shall be according to NEMA. When required, this feature shall be internal to the detector.
1079.02 Detector Loop and Sealer.
a.Wire. Detector loop wire is classified into three types as follows.
1.Type I detector loop wire and the loose encasing shall be according to IMSA 51-5.
2.Type II detector loop wire shall be No. 16 AWG, mineral-insulated, copper sheathed cable. The conductor shall be insulated with magnesium oxide and enclosed in a seamless copper sheath with a polyethylene jacket. A terminal subassembly kit composed of a pot, cap, sealer, and sleeves shall be supplied with the cable.
3.Type III detector loop wire shall be No. 14 or 16 AWG, Type THWN, THHN, or XHHW, with stranded copper conductor.
b.Preformed Detector Loop. The preformed detector loop shall be either of the following.
1.Rigid Plastic Conduit. The rigid plastic conduit shall be 5/8 in. (16 mm) outer diameter schedule 80 PVC or polypropylene conduit. All bends shall be a 6 in. (150 mm) radius minimum and shall be integral to the conduit.
2.Heavy Duty Reinforced Rubber Hose Conduit. The heavy duty reinforced rubber hose conduit shall be Class A oil resistant, hydraulic- type rubber hose reinforced with synthetic cord. It shall have an inner diameter of 3/8 in. (9.5 mm) and an internal pressure rating of 250 psi Fabric Materials Art. 1080.01 (1,720 kPa). The loop shall be preformed with a sealed tee connection, and shall be part of one continuous piece with initial lead-in connection wires. No joints or splices shall be made in the loop or wire, except for their connection to the lead-in wires located outside of the pavement.
c.Sealer. The Sealer for Type I detector loop shall be one of the following.
1.Polyurethane or Two-Component Polyurethane Modified Asphalt. The material shall be cured to be rubber like, and suitable for sealing detector loops in both hot-mix asphalt (HMA) and concrete pavements. The cured material shall be highly resistant to oil, gasoline, salts, acids, and alkalis.
2.Two Component Epoxy or Two Component Polyester Resin. The material shall be cured to be flexible, and suitable for sealing detector loops in both HMA and concrete pavements. The cured material shall be highly resistant to oil, gasoline, salts, acids, and alkalis. The above material shall have the following properties. Property Value Pot life at 77 °F (25 °C) 13 minutes minimum Cure Time 4 hours maximum Shore D Hardness 28 minimum OTHER ITEMS SECTION 1080. FABRIC MATERIALS
1080.01 Fabric Envelope for Pipe Underdrains. The fabric envelope for
encasing pipe underdrains may be either a knitted, woven, or nonwoven fabric.
a.Fabric Materials. Fabric materials shall be as follows.
1.Knitted Fabric. Knitted fabric envelope shall be Type A according to ASTM D 6707 and be a continuous one piece knitted polymeric material that fits over the pipe underdrain like a sleeve. It shall be free from any chemical treatment or coating that might significantly reduce porosity and permittivity.
2.Woven or Nonwoven Fabric. The fabric shall be Class 3 according to AASHTO M 288 and consist of woven yarns or nonwoven filaments of polyolefins or polyesters. Woven slit film geotextiles (i.e. geotextiles made from yarns of a flat, tape-like character) shall not be permitted. The yarns or filaments shall be dimensionally stable (i.e. maintain their relative position with respect to each other) and resistant to delamination. The yarns or filaments shall be free from any chemical treatment or coating that might significantly reduce porosity and permittivity.
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Source: Illinois Standard Specifications for Road and Bridge Construction, 2022 Edition. Pages 1049–1050 of 1,217. View official source ↗